Dual string hydraulically actuated oil well packer

ABSTRACT

A simplified and efficient dual string hydraulically actuated packer assembly is disclosed which utilizes unitary tubular anchor means, compressible packer elements, and spring-loaded, shearable, ratcheting packer lock means.

llnite Patent 1 .llett 1 DUAL STRING HYDRAULICALLY ACTUATED 01L WELLPACKER [75] Inventor: Marion Barney Jett, Seagoville, Tex. [73]Assignee: Dresser Industries, Inc., Dallas, Tex. [22] Filed: Nov. 2,1973 [21] Appl. N0.: 412,221

[52] US. Cl 166/120, 166/134, 166/237 [51] Int. Cl. E21b 23/06, E21b33/122 [58] Field of Search 166/120122,

[56] References Cited UNITED STATES PATENTS 1/1965 Sizer ..166/1206/1965 Cochran 166/120 1610 16Gb I60 I68 ,lan.7,1975

3,211,226 10/1965 Myers et a1. 166/120 3,288,218 11/1966 Young 166/120 X3,381,752 5/1968 Elliston 166/120 3,548,936 12/1970 Kilgore et a1.166/121 3,714,984 2/1973 Read 166/206 X 3,731,740 5/1973 D0uglass....166/120 3,779,314 12/1973 Read 166/216 3,804,164 4/1974 Ellis 166/120Primary Examiner-David H. Brown Attorney, Agent, or Firm-Michael J.Caddell [57] ABSTRACT A simplified and efficient dual stringhydraulically actuated packer assembly is disclosed which utilizesunitary tubular anchor means, compressible packer elements, andspring-loaded, shearable, ratcheting packer lock means.

10 Claims, 36 Drawing Figures PATENIED JAN T1975 SHEET 01 0f 13 PATENTEDJAN 7375 SHEET 02 8F 13 PATENTED JAN 7 i 5 SHEET 030F113 PATENTEU JAN 7L975 saw on or 13 FIG. 8

PATENTED '7l975 3,858,648

FIG. 7

FIG. 7A

PATENTED JAN 7 I975 SHEET OB 0F 13 PATENTED 3,858,648

sum OBGF 13 FIG. II'D FIG. HE

F e. I F

FIG.I3

FIG. l4

PATENTEDJAN #1915 a. 858,648

SHEU IUUF 13 FIG. I5A FIG. I5B

PATENTEU 71975 I $858,648

SHEET llUF 13 FIG. I6A

FIG. I6B' DUAL STRING HYDRAULICALLY ACTUATIED OIL WELL PACKER BACKGROUNDOF THE INVENTION Often during the producing life of an oil well itbecomes desirable or necessary to produce from two or more differentunderground formations penetrated by the wellbore. This is commonlyachieved through the use of packer assemblies containing two or morestrings of conduit passing therethrough.

An example of such apparatus is shown in U.S. Pat. No. 2,965,173 inwhich a packer apparatus having dual conduit strings passingside-by-side therethrough has located on its outer surface resilientsealing cups having outwardly flared ends which are moved into sealingengagement by fluid pressure differentials above and below the cups.

Other types of multi-string packers include the inflatable or bladdertype such as disclosed in U.S. Pat. No. 2,991,833 and the hydraulicallyactuated, compressible element, multistring packer such as disclosed inU.S. Pat. No. 3,167,127. All known multi-string packers using mechanicalanchors to lock the assembly to the casing wall utilize the wedge-typeslip segments having teeth which are cammed or wedged into contact withthe casing wall by the action of a wedging mandrel being forced insidethe slip segments forcing them outwardly into contact with the casing.Other known types of slips include the hydraluic button type which arespring-retained radial pistons slidably located in the wall of thepacker body and actuated outwardly against the spring retainer byhydraulic force applied from inside the packer assembly. An example ofthe button type slips is shown in U.S. Pat. No. 3,311,169.

The dual-string or dual-conduit packers normally are used with astandard single string packer located on the tubing string below thedual-packer, which tubing string communicates with a lower formationbelow the standard packer and is connected to one conduit in the dualpacker and from there to a tubing string passing to the surface. Thesecond formation is normally located between the standard packer and thedual packer and can be produced through the second conduit passingthrough the dual packer and communicating with a second tubing stringextending to the surface.

The disadvantages of the prior art dual string packers are theircomplexity, extended length, and the tendency of the wedge-type slips tobecome disengaged by shifting or stretching of the tubing and/or casingduring the production life of the packer.

These and other disadvantages of prior devices are overcome by thepresent invention which comprises a dual string packer having simplifieddesign, shortened length, and highly efficient tubular unitary slipmeans.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of the dualpacker assembly;

FIGS. 2A and 23 comprise a lateral cross-sectional view of the assemblytaken at line 2-2 of FIG. 1;

FIGS. 3A and 3B comprise a lateral cross-sectional view of the assemblyalong line 3-3 of FIG. 1;

FIGS. 4A and 48 comprise a lateral cross-sectional view of the assemblytaken along line 4-4 of FIG. 1;

FIG. 5, shows an axial cross-sectional view of the assembly taken atline 5-5 of FIG. 2;

FIG. 6 is a cross-section side view of the improved unitary tubularslip;

FIG. 7 is a top view of the improved unitary slip;

FIG. 7a is a side view of the improved unitary slip;

FIG. 8 illustrates a cross-sectional view of the apparatus in itsengaged position;

FIG. 9 illustrates the top view of an alternate embodiment of theapparatus;

FIGS. 10A through 10C comprise a cross-sectional view of the embodimentof FIG. 9 taken at line 10-10 in FIG. 8; 7

FIGS. 11a through 11c are cross-sectional views of the embodiment ofFIG. 9 taken at line 11-11;

FIG. 11d is a cross-sectional axial view of a key retaining sleeve;

FIG. He is a side cross-sectional view ofa key retaining sleeve;

FIG. 11f is an axial end view of a retaining key;

FIGS. 12A through 12C comprise a cross-sectional view of the embodimentof FIG. 9 taken at line 12-12 of FIG. 9;

FIG. 13 is an isometric view of the shearable ratchet pins;

FIG. 14 is an isometric view of one of the setting cylinder releasingkeys in the piston assembly;

FIGS. 15a and 15b are schematic cross-sectional views of the grippingteeth on the anchor slip;

FIGS. 16a and 16b show axial and radial crosssectional views of thewedge-cone heads dissassembled from the apparatus;

FIG. 17 illustrates a cross-sectional view of the slip of the secondembodiment;

FIG. 18 shows a side view of the slip of FIG. 17;

FIG. 19 is an axial cross-sectional view of a mandrel locking assembly;

FIG. 20 is a lateral cross-sectional side view of the mechanism of FIG.19 taken at line 20-20;

FIG. 21 is a lateral cross-sectional top view of the mechanism of FIG.19 taken at line 21-21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of theinvention is illustrated in FIGS. 1 through 5 in which a packer assembly1 is comprised of an upper mandrel assembly head 2, resilient packerassembly 3, upper slip 4, lower slip 5, and piston assembly 6, allmounted more or less in encircling relationship about primary mandrel 7and secondary mandrel 8.

The upper mandrel assembly head consists of an integral cylindricalmandrel head 9 having longitudinal parallel bore passages 10 and 11passing therethrough having internal threaded sections 10a and 11a inwhich are threadedly engaged by cylindrical tubular elongated mandrels 7and 8. A receiver collar 12 is connected by bolts 13 to mandrel head 9and has bore passages 10b and 1 1b coinciding and axially aligned withpassages 10 and 11 of head 9. Collar 12 has a concave cupped uppersurface 12a arranged to guide a tubing string connector 14 into bore 11bof the assembly. Mandrel head 9 further has a threaded internal sectionadapted to receive a section of conduit or tubing in threaded engagementtherein.

Tubular mandrels 7 and 8, fixedly attached by threaded connection tohead 9, extend in parallel relationship to the longitudinal axis of thepacker assembly 1 and generally parallel to the well-bore and havebottom threaded sections 7a and 8a extending downward out of the pistonassembly 6 whereby either or both may be threadedly engaged into a lowertubing string extending downward into the wellbore.

Slidably mounted on mandrels 7 and 8 are, in descending order, the upperunitary slip 4, upper packer head 31, one or more resilient packerelements 32, and lower packer head 33. Upper and lower packer heads 31and 33 are metal cylindrical plates having a cupped surface on one sideand having two axial bores therethrough for receiving mandrels 7 and 8.

Resilient packer elements 32 are made of a resilient material such assynthetic rubber and are generally cylindrical, with dual bore passagespassing axially therethrough to snugly receive mandrels 7 and 8. Packerelements 32 are located in close fitting relationship with each otherand with the cupped surfaces of plates 31 and 33. A flanged retainerring 34 abutting an external shoulder 18 on mandrel 8 limits downwardmovement of the resilient packer assembly 3 on the mandrels by alsoabutting the lower surface of lower head 33.

Lower unitary slip 5 is located on the mandrels in encirclingrelationship about the mandrels and slidably mounted thereon; slip 5 issimilar to slip 4 but is mounted on the mandrels in an invertedorientation to slip 4.

Piston assembly 6 is mounted on mandrels 7 and 8 in encirclingrelationship and consists of cylindrical setting piston 61 andcylindrical setting cylinder 62. Setting piston 61 is a substantiallysolid cylindrical piece having dual axial bore passages therethrough toreceive mandrels 7 and 8 and an upper annular space 63 around mandrel 8.Referring to FIG. 5, setting piston 61, as shown in cross-section, has aplurality of transverse lateral cylindrical bore passages 64intersecting the longitudinal axis of bore passage 11 and havinginternal helical threads. Shearable cylindrical ratchet pins 65 areslidably located in passages 64 and are urged into engagement withmandrel 8 by the expansive forces ofleaf, helical, or belleville springs66 which are held in compression against pins 65 by abutting engagementwith threaded plugs 67 which are snugly secured into threaded passages64.

Pins 65 (see FIGS. 5 and 13) have a reduced section 65a designed toshear at a predetermined load and a toothed ratchet head 65b having acurved face adapted to match the curvature of mandrel 8, with aplurality of cammed teeth 65c thereon designed to match and engageexternal annular teeth 8b formed on mandrel 8. FIG. 13 illustrates asecond view of the shearable ratchet pins showing the relationship ofthe teeth 650 on ratchet head 65b. The teeth 8b and those on head 65bare arranged to allow upward movement of the pins on mandrel 8 butprevent downward movement of the pins and thus prevent downward movementof piston 61. The cammed faces of teeth 8b and 650 allow the piston 61to move upward by camming the pins back against the springs 66,compressing them and allowing the ratchet teeth to slide over oneanother. Upon attempted downward movement of piston 61 on mandrel 8 theperpendicular faces of teeth 65c abut the perpendicular faces of teeth8b and prevent the backward motion. Further operation and function ofthe ratcheting arrangement will be described in connection withoperation of the entire packer assembly.

Setting cylinder 62 is a cylindrical element having a substantiallysolid lower section 62a and an upwardly 4 extending outer collar 62bpassing exteriorly around piston 61. Lower section 6211 is solid exceptfor two longitudinal bore passages therethrough which receive in snugslidable relationship the mandrels 7 and 8. Cylinder 62 is temporarilyattached to piston 61 by means of a plurality of shear pins 68 passingthrough upper collar 62b in threaded engagement therewith and seating inexterior channel 610 passing circumferentially around piston 61.

Setting cylinder 62 is temporarily attached to mandrel 8 by means ofaplurality of curved locking keys 69 having inwardly projecting shoulder69a thereon for engaging a matching exterior channel in mandrel 8. Keys69 are held inward by overlapping abutment of annular shoulder 61b onthe lower end of piston 61. The keys, by abutment with the groovedchannel in mandrel 8, the lower end of piston 61, and the upper end ofsolid end 62a of cylinder 62 temporarily prevent any sliding motion ofthe piston assembly 6 with respect to mandrels 7 and 8. One or moreports located through the wall of mandrel 8 to communicate with the areabetween piston 61 and cylinder end 62a from bore 11 to release keys 69in a manner which will be more fully described in relation to theoperation of this tool.

At the lower end of mandrel 8 on external threaded end 8a is a standardthreaded collar 19 attached thereto containing a valve seat 21 forreceiving a fluid valve member such as a ball or plug, arranged toselectively close passage 11 to fluid flow through mandrel 8 and allowfluidic pressure to be applied through ports 80.

Referring specifically to FIGS. 2 and 4, the tubing string connector 14is more particularly described as a cylindrical tubular upper sleevehaving internal threads 14a for engaging a standard conduit section andan annular external depression 14b for receiving a seal carrier ring 15.A lower spring collet sleeve 16 is threadedly attached at 16a to theupper sleeve 14c and has collar 16b thereon for abutting and retainingcarrier ring 15 which has a plurality of circular seals 17 thereon forsealing engagement between connector 14 and head 9.

Collet sleeve 16 is temporarily restrained in head 9 by the abutment ofannular exterior shoulder with interior annular projection 9a in head 9.Removal of shoulder 16c upward past projection 9a can be accomplished byapplication of a predetermined lifting force which causes inwarddeflection of the shoulder 16c and allows it to move upward pastprojection 90. Deflection inward of shoulder 16c is made possible by theforming of several longitudinal slots 16d in collet sleeve 16 therebylending flexibility to the metal remaining in the areas between theslots. The amount of lifting force required to move collet sleeve 16 outof head 9 can be adjusted as desired by the number and/or width of slots16d and/or the angle of engagement between 160 and 9a.

Referring now to FIGS. 6, 7, 7a, 15a, and 15b, a more detaileddescription of the improved unitary slip members can be given. Each slip4 and 5 comprises a generally cylindrical gripping unit having on theextended outer reaches of opposing sides a plurality of teeth 41 curvedabout the slip body with an axis of curvature at an angle to the centrallongitudinal axis of the slip member. The teeth are also arranged sothat the intersection of a plane passing through the slip longitudinalaxis with the teeth extreme outer tips would circumscribe a curve asshown in FIGS. a and 15b. This is to allow the use of this apparatus incasings having varying inner diameters and obviates the need for aseparate set of unitary slips for each weight rating of casing. Insmaller ID casings, as shown in FIG. 15a, i.e., those of heavier weight,the two sets of teeth near the center of the slip, having the shortestdistance between them will contact the casing wall with greatest areacontact; while in larger ID, lighter weight casing as shown in FIG.115b, the teeth at the two outer ends of the slip will contact thecasing due to the greater distance between the upper outer teeth and thelower outer teeth.

The curved boundary tooth profile as shown in FIGS. 15a and 15b allowsthis versatility of use by providing greater tooth-casing wall contactarea regardless of which teeth are called upon to anchor the packerassembly.

Looking at FIGS. 6, 7 and 7a, it is clear that each unitary slip has adual-axis bore passage for each mandrel to pass therethrough. One axisof each bore passage generally parallels the central longitudinal axisof the slip and the other axis is located at an angle thereto in thesame plane.

In FIG. 6, the intersecting bore passages are illustrated more clearlyand their longitudinal axes are designated as XX and Y-Y. This view istaken from the side with the two mandrels lying in line with one anotherso that only one can be seen in cross-section. The axis XX defines borepassages 43 which are shown by the dashed lines in the figure. When theslip is oriented so that the mandrels occupy these bore passages, thegripping teeth are at their innermost orientation, out of contact withthe casing wall.

When the slip has been rotated to bring the passages M into fittingrelationship with the mandrels, then the gripping teeth are at theiroutermost extension from the mandrels and can engage the casing wall.Bore passages M are shown by the solid lines in the figure.

The angle between axes XX and YY can be from five degrees up to about 35degrees but preferably is around 18 to 20 degrees.

Referring specifically to FIG. 6, a significant improvement in theunitary anchor slip 5 is illustrated in the cross-sectional view whichshows the abutment surface 51. This surface is at the opposite end ofthe slip from abutment edge 52 and provides a dual purpose surface onthe slip.

Rotation of the slip into casing engagement is achieved by moving anabutment means such as piston 61 against compound surface 511 whichmoves the slip along the mandrel until abutment edge 52 encounters anopposing abutment surface. The resultant effect in a rotational momentestablished in the slip from the reactant force on edge 52. This isaided by abutment forces introduced into the slip from surface 51.

Surface 51 has been termed a dual or compound surface. This is becauseof the flat portion 511a and the tangentially curved section Slb joiningthe flat surface. The curve of surface 51b is preferably on a radius Rsubstantially equivalent to VzL where L is the axial length of the slipalong axis XX. The curved surface is tangential to flat surface 51a atthe point where axis XX intersects the end of the slip at surface 51.

The slip is arranged to pivot about a point C located at theintersection of axes XX and YY at a distance of approximately one-halfof the slip length L from surface 51.

A phantom line P is drawn on the slip at the edge containing surface 51bto indicate the construction of the prior art slip means. Such a slip isdisclosed in US. pat. No. 3,739,849 to Robert B. Meripol. While the slipof that disclosure is a significant improvement over the art, theexistence of the extended shoulder P requires significant additionalapparatus in the packer on which it is used.

Primarily a significant clearance must be maintained with the prior artslip between the slip in its unset position and the lower abutment meansto allow pivoting of the slip into casing engagement position. This isbecause the radius Rp is considerably greater than the distance /2L andtherefore a minimum clearance equivalent to Rp R must be maintainedbelow the flat surface of the prior art slip to allow it to rotate intothe set position.

To maintain the clearance and also to support the slip in a rotatableposition and allow a moment force to be applied to abutment surface 52without driving the slip downward on the abutment surface, the prior artslip was necessarily supported by pivot pins at C which passed throughthe slip and were engaged in an inner support sleeve. The downward forceat 52 was countered by the oppositely reacting upward force of the pinson the slip which set up the desired rotational moment. The inner sleeveand the pins also served to hold the slip up off of the lower abutmentmeans so that it could be pivoted. The inner sleeve and pivot supportpins are illustrated in FIG. I of the aforementioned Meripol patent anddesignated therein as 20 and 34 respectively. The clearance under theslip is not illustrated in that figure since the slip has been rotatedto the engaging position.

The improvedslip of this invention eliminates the need for thesupporting sleeve, the pivot pins, and the pivot clearance necessary tothe prior art device.

Since the radius of the curvature of surface 51b about the pivot centerC is equivalent to the distance of surface Sla from C, it is obviousthat the slip 5 can be pivoted about C in the same space as thatoccupied by the slip in the unset position. This eliminates the need forthe support sleeve, the pins, and the clearance below surface Sll.Furthermore surface 511 may remain in constant abutment with adjacentabutment means to provide the necessary rotational moment from forces onsurface 52 which further obviates the need for support pins at C.

Another advantage of the improved slip is in the guaranteed setting ofthe slip. In the aforementioned patented slip, should the clearancebelow the slip ever be decreased due to stretching of the parts,accumulated debris in the clearance area, failure of one or more of theparts, or incorrect assembly of the tool during manufacture, to thepoint where the clearance is substantially less than the amount Rp-wzL,it is clear that edge P will abut the lower surface or the debris inopposition to the setting forces at edge 52 and the desired rotationalmoment about C will be cancelled.

This situation is non-existent since the slip can rotate without theneeded clearance and due to the simplicity of having no pins, norsleeves; and incorrect assembly and part failure are almost absolutelyeliminated.

One further advantage of the improved slip is that, when used as thelower slip, should it become lodged in the casing to the point that thereleasing spring 49b hereinafter described is insufficient to rotate itout of engagement, dislodgement can be accomplished by merely bumpingupward on the slip with the lower abutment means. Since some point onthe curved surface lb will be located directly below C and will receivethe upward abutment is is clear that no rotational moment will beintroduced into the slip, and the simple upward driving force, inaddition to the disengaging force of the releasing spring 49b willdislodge the slip from the casing. The upper surface 52 will of coursebe free from abutment during this releasing step.

Although the slip 5 has been described above, it is emphasized that slip4 is identical to slip 5 and operates in the same manner, and the abovedescription appertains thereto as well. Thus it can be seen that thesetwo side-by-side dual bore passages and the compound curved-fiatabutment surface 51 allow the unitary slip to pivot about the twoparallel mandrels 7 and 8 from a non-engaging position to a casingcontact position without any interference between the slips and themandrels.

Each slip also has a releasing slot 46 as shown in FIG. 3 which runspartially the length of the slip and passes through the wall thereof ina plane perpendicular to the plane of the two dual-axis bore passagesand the central slip axis. A third bore passage 47 passes from the innerterminal wall 46a of the slot 46 through the slip to the opposite end.The cross-sectional view of FIG. 3 reveals the purpose of slot 46 andpassage 47 to be for the location of the threaded L-shaped releasing lug48 and release spring 48a in the upper slip 4; and in the lower slip 5,retaining bolt 49, flanged bolt collar 49a, and coil spring 49b. Aspring cavity 49c is formed in each slip and a spring cavity 48b isformed in the L-shaped bolt to receive coil spring 48a. Lug 48 passesthrough passage 47 and is threadedly secured into the lower end of head9. Likewise, bolt 49 passes through passage 47 of the lower slip 5 andis threadedly secured to the upper end of setting piston 61.

In FIGS. 2 through 5 the packer assembly is illustrated in its unsetorientation with the mandrels 7 and 8 lying in bore passages 43 parallelto the central longitudinal axis. In FIG. 8 the packer apparatus hasbeen activated and expanded into sealing and anchoring engagement withthe casing wall. In this position, the slips have been rotated to bringthe mandrels into the second bore passages 44 at the angle to thelongitudinal bore passages 43 mentioned above.

OPERATION OF THE PREFERRED EMBODIMENT In a typical use of the describedapparatus in a dual zone formation the apparatus is interconnected intoa tubing production string by threaded connection of threads 10c and 7ato mating threads of standard tubing sections. The string will have astandard packer located in the string below this apparatus capable ofsealing off the annulus between the tubing and the casing at thepredetermined desired time.

The tubing string with the standard packer and the packer apparatus 1 islowered into the well until the lower packer passes the upper producingformation and is situated between the two subject formations. The packerapparatus 1 will be located above the upper producing formation.

By appropriate means, such as manipulation of the tubing or hydraulicpressure applications, the lower packer is set in the casing.Alternately, the lower packer may be set by wireline or other meansbefore the primary and secondary tubing strings are lowered into thehole and then the primary string can be strung into the lower packer.The second production string may then be lowered down the well with theconnector sleeve 14 threadedly attached at the lower end. When thestring has been lowered sufficiently, the sleeve 14 will engage head 9and snap into place. The second string will then be sealinglycommunicating with mandrel 8 via bore 11 of head 9.

A sealing ball or plug 20 is dropped run in on a wireline, or pumpedinto the secondary tubing string to seal on seat 21 and allow fluidpressure to be applied to the fluid in the secondary string and actthrough bore 11 and ports against the lower end of the setting piston61. When sufficient pressure has been reached in bore 11, piston 61 willshear pins 68 and move upward against the lower edge 51 of lower slip 5sliding the slip upward until upper abutment edge 52 of the slipcontacts the lower edge of lower head 33. Movement upward of piston 61on mandrel 8 is allowed by the ratcheting action of ratchet pins 65 overmandrel teeth 8b which ratchet mechanism simultaneously preventsdownward movement of piston 61 on mandrel 8 under normal operatingconditions.

As piston 61 moves upward in response to hydraulic pressure actingupward, the upward force is transferred to lower slip 5, and from slip 5to packer elements 3 and into the upper slip 4. This abutment of theslips with the packer assembly serves to rotate the slips into contactwith the casing simultaneously with compression of the packer elements32. Thus, continued application of hydraulic pressure of sufficientmagnitude for a short period of time will set the two unitary slips intothe casing and will expand the resilient packer elements outward intosealing engagement with the casing as shown in FIG. 8.

Upon release of hydraulic pressure in bore 11, the resilient packerelements will attempt to expand longitudinally and contract radially.This will provide a constant upward force on slip 4 and a constantdownward force on slip 5 maintaining them engaged in the casing. Also,ratchet pins 65 will maintain mandrel 8 telescoped within piston 61thereby preventing the packer from unsetting should mandrel 8 try tomove upward in the wellbore for any reason.

Should it become desirable to unseat the packer apparatus 1, this can bedone selectively by applying an upward force on mandrel 7 and thus onmandrel 8 sufficient to shear pins 65 through their reduced area 65a. Inorder to prevent a bending or collapsing of shear head 65b along the gapat 65a, a relatively soft filler material such as lead or plastic can befilled in the gap at 6511 to absorb the bending moment and insure propershearing of the pins.

Upon shearing pins 65 mandrels 7 and 8 move upward with respect to theslips 4 and 5 and packer assembly 3. Releasing lug 48 will move upwardand work through spring 48a to pivot upper slip 4 back to itsnonengaging position, also pulling it upward off of the packer assembly3, allowing the resilient packer elements to contract to their normalunseated orientation. Continued upward movement of the mandrels 7 and 8will disengage the lower head 33 from abutment shoulder 52 of slip 5allowing disengagement of the lower slip from the casing. Coil spring49b will then expand against slip 5, thereby pivoting slip into itsretraccted position. The packer assembly 1 is now completely unset andmay be removed from the hole. The secondary tubing string may be removedfrom passage 11 before or after unsetting the packer assembly 1, or maybe removed from the hole with the primary string if desirable.

MANDREL LOCKING MEANS FOR HIGH WELL PRESSURES Occasionally the apparatusof this invention must be used in a well having extremely high formationpressures or used in treatments of wells whereby fluids under highpressure must be pumped into the well formations through this apparatus.

For instance, pressures below the above described packer assembly mayreach the range of 5,000 PSI or higher, and in this range a considerableupward force is exerted by the fluid upon the conduit strings in thewellbore, creating a buoyancy effect on the packer mandrels tending todrive them upward through the packer assembly resulting in unsetting ofthe slips and consequently the packer elements. This bouyancy effect istermed the piston or end area effect.

To avoid this tendency towards disengagement of the slips caused by thepipe bouyancy, a special locking mechanism is provided which is actuatedby pressure below the packer elements and serves to lock the mandrels inthe packer assembly.

Referring to FIGS. 19, 20, and 21 the locking mechanism is illustrated.FIG. 19 is an axial view in crosssection taken at line 1919 of FIG. 20.In the modified embodiment, the packer assembly 3 of FIGS. 1-4 isreplaced by the modified locking packer assembly 203. Packer assembly203 consists essentially of an upper head 231, resilient packer elements232 and lower head 233, all encircling mandrel 7 and modified mandrel208.

Modified mandrel 200 is substantially similar to mandrel 8 except forthe existence of a plurality of tooth ridges 210 formed in the outersurface of the mandrel. Each ridge 210 has an abrupt upper face 210a anda sloping lower face 21012. The angle that face 210a makes with a planenormal to the tubular axis of mandrel 208 is preferably about tendegrees but may vary from 1 to 40 degrees depending upon the amount ofrestraining force desired. The angle of face 21% with face 210a may befrom 130 degrees to about 50 degrees with a preferable angle of around90 degrees. Ridges 210 preferably circle mandrel 200 entirely but thisis not absolutely essential.

The packer assembly 203 contains two fluid bore passages 204 and 205passing through lower head 233, resilient packer elements 232, and partof the way into upper head 231. The bore passages generally run parallelto the mandrels 7 and 208 and communicate with the formation annulararea below the packer assembly 203.

Rigid tubes 206 and 207 line the bores through the resilient elements232 to prevent collapse and closure of the passages upon compression anddeformation of the resilient packer elements.

The bore passages 204 and 205 intersect pin channels 211 and 212 passingfrom the longitudinal bore passages 209 in head 231 containing mandrel200, going radially outward from mandrel 208 through head 231 andthrough the outer surface of the head.

The radial passages 211 and 212 contain outer threaded portions 211a and212a and smooth piston sections 21% and 212b. The radial passagespreferably are of a cylindrical configuration for ease and convenienceof manufacture but may be of any reasonable configuration.

Located slidably in piston sections 2111) and 21212 of the radialpassages are locking pistons 213 and 214 having curved toothed faces213a and 214a. The teeth on these faces match and complement the teethof mandrel 208 so that full surface contact between the two sets ofteeth will occur. The radius of curvature of faces 213a and 214a issubstantially equal to that of the outer surface of mandrel 208.

Threaded sections 211a and 212a contain threaded plugs 215 and 216snugly engaged therein in sealing contact, which plugs, in conjunctionwith pistons 213 and 214, serve to form hydraulic expansion chambers 217and 218 in each radial passage. Circular seals 219 and 220 in the outerwall of pistons 213 and 214 serve to prevent leakage of fluid from theexpansion chambers into the mandrel bore passage 209.

Operation of the locking mechanism is automatic when this modifiedembodiment of packer mechanism 203 is installed in the previouslydescribed packer apparatus l, and consists of hydraulic pressure fromthe annular area below the packer mechanism 203 communicating throughbores 204 and 205 and into pressure actuation chambers 217 and 218. Thepressure is prevented from moving radially outward by plugs 215 and 216and therefore it acts inwardly against the pistons 213 and 214 drivingthem against the mandrel teeth 210 thereby gripping the mandrel 208 andholding it in the packer assembly 203.

Since the packer anchors 4 and 5 are normally released by pulling upwardon the tubing strings and thus on the mandrels, the angle of faces 210aon the mandrel teeth should be around five to fifteen degrees to allowupward movement of the mandrels upon application of external liftingforce on the mandrels. Also, the pressure area of piston faces 213 and214 may be designed so that the gripping force of the piston teeth onthe mandrel teeth is just equal to or slightly greater than the bouyantupward force on the mandrels so that little additional upward lifting ofthe mandrels is required to wedge the piston teeth out of engagementwith the mandrel teeth when unsetting the packer to remove it from thewellbore.

It should be noted that the back or lower edges 21% of the mandrel teethare at a relatively flat angle compared to the upper faces 210a so thatmovement of the upper head upward on the mandrels is hardly impeded.

In additijon to the hydraulic force on pistons 213 and 214 it is clearthat any known spring means such as coil springs could be compressed andplaced in chambers 217 and 218 to supplement the actuating pressure.

ALTERNATE EMBODIMENTS Referring now to FIGS. 9 through 12 and 16 through18, an alternate embodiment of the invention is disclosed which utilizesa single unitary slip or anchor capable of anchoring the assembly in thecasing against upward and downward forces and pressures.

The packer apparatus 101 essentially comprises upper connector assembly102, upper head assembly 103, packer assembly 104, unitary slip 105, andpiston assembly 106.

The upper connector assembly 102 features a primary tubing receiver 110which is an elongated tubular member having external threads 110a and110b at its upper and lower ends and containing a connector collar 111threadedly attached to threads 110a and arranged to be interconnectedinto a standard tubing string. Tubing receiver 110 is threaded intoupper head 112 which also receives in threaded engagement a tubularelongated secondary tubing string receiver 113. Head 112 is primarily acylindrical member having dual bore passages passing therethroughoriented substantially parallel with the central longitudinal axis ofthe cylindrical member. The upper portions of the dual bore passageshave internal threads 112a for receiving tubular sections 110 and 113.

Tubular receiving member 113 has an enlarged chamber area 114 attachedto a standard tubular section or neck 115 and containing an annularinwardly projecting shoulder 116. Threadedly attached to the upper endof member 113 at threads 113a and slidably encircling member 110 isupper receiver disk 117 which is a generally cylindrical section havinga concave upper face 121 and dual bore passages 119 and 120 to receivemember 110 and the secondary tubing string collet sleeve 118. Colletsleeve 118 is a tubular member having an annular shoulder 123 sized toabut shoulder 116 and be retained thereby. Longitudinal slots 122 areformed through the wall to give the remainder of the sleeve flexibilityand allow shoulder 123 to flex inward and traverse shoulder 116. Acylindrical, tubular seal carrier collar 124 is threadedly attached tosleeve 118 and contains seal elements 125 encircled thereon to sealagainst bore 114 of receiver 113. A standard length of tubing 126 can bethreadedly attached into collar 124.

Upper head 112 contains inner annular abutment ridges 112b in borepassages 130 and 131 to receive in snug fitting relationship the primaryand secondary mandrels 107 and 108 which mandrels are elongatedcylindrical tubular members extending substantially through the entiretool.

Each mandrel 107 and 108 has an annular exterior shear shoulder 107a and108a for abutment with and selective shear means for shear screws 127which project through the wall of head 112 and into the shear chamber128 formed between head 112, shoulders 107a and 108a and madnrels 107and 108.

A cylindrical abutment shell 129 is secured to head 112 by threadedbolts 132 passing through the head and threadedly engaging shell 129 asshown in the discontinuous cross-sectional view of FIG. 9. This crosssection must be shown in broken or discontinuous section in order toshow the bolts since a normal cross section at line -10 of FIG. 9 wouldnot clearly show them.

Located axially within shell 129 are two parallel locking-key retainersleeves 133 and 134 which are relatively thin cylindrical sleeves havingflats milled along diametrically opposing sides and placed side by sideslidably telescoped over mandrels 107 and 108. The milled sides areshown in cross section in FIG. 12 and the normal sides are shown in FIG.10. FIG. 11d shows a cross-sectional axial view of one of thekey-retaining sleeves 133 and 134, and FIG. He shows a crosssectionalaxial view of a sleeve.

Shell 129 also consists of a thick wall area and a thin wall area asshown in FIGS. 11 and 12. The narrowed walls of shell 129 and of sleeves133 and 134 are to allow side by side placement of the two mandrels 107and 108 within the dimensions of the sleeves and the shell. shell 129has at its lower end an inwardly projecting flange 129a through whichpass locking collet sleeves 135 and packer assembly bolts 136concentrically located within sleeves 135.

Sleeves 135 each have a small spring lip 135a on the outer edge of theupper end for engaging flange 129a and an outer abutment flange 135b atthe lower end for abutment and retention of upper packer plate 137 tohead 112. This prevents head 112 from floating upward on bolts 136 awayfrom plate 137 and prematurely shearing of screws 127 while going in thehole with the tool.

Key-retaining sleeves 133 and 134 are arranged so that slots in thesleeves are located directly over parallel, exterior circumferentialridges 138 and 139 on mandrels 107 and 108. Retaining keys 140 aresnugly fitted within the slots and abut the mandrels between the ridgesas shown in FIG. 9. This arrangement temporarily locks the mandrels tothe upper head assembly 103 by means of keys 140, ridges 138 and 139 andsleeves 133 and 134 and allows the operator to pick up on the string andreciprocate it to dislodge sediment or other material which may bebinding between the tool string and the casing while going in the hole.This protects shear pins 127 from premature shearing. Keys 140 are heldwithin the slots in sleeves 133 and 134 by abutment with the inner wallof the lower extending portion of head 112. FIGS. 11a 11c give views ofthe sleeves and keys disassembled from the apparatus for a betterunderstanding of their structure.

The resilient packer assembly is located slidably about the mandrels 107and 108 below upper packer plate 137 and consists of resilient packerelements 141, rigid spacer plates 142 and lower packer plate 143.

A dual wedge-cone head 144 is abutted against lower plate 143 inencircling relationship about mandrels 107 and 108 and wedge anchors145. Anchors are wedge shaped inserts having a plurality of angledgripping teeth on their inner surface contacting the outer wall of themandrels.

Movement upward of the anchor inserts 145 on the mandrels is possiblebecause of the angle of the upper faces of the wedge teeth but movementdownward on the mandrels is prevented by the' perpendicular teeth faceprojecting into the mandrel surface and also because of the wedgingforce inward imposed by the action of the wedge-cone head 144. It isclear that the angled inner surface 144a of head 144, acting on theangled outer surface 145a of the anchor 145 as the anchor moves upward,will result in a pressing inward of the anchor insert upon the mandrelit contacts thereby preventing downward movement of the mandrel. A moredetailed view of the dual wedge-cone head 144 is shown in FIGS. 16a and16b.

Guide pins 146 project through head 144 and into slots 145b formed inthe outer portion of wedge inserts 145 to prevent the anchors fromrotating around on the mandrel and getting out of optimum grippingposition which is with each anchor diametrically opposed to anotheranchor about the mandrel.

A thin cylindrical retaining sleeve 147 snugly encircles head 144 andabuts lower plate 143 and cylindrical anchor cap 148 which is slidablyaligned on mandrels

1. A dual string oil well packer comprising: dual elongated tubularmandrels arranged in substantially parallel orientation, each having anintegral independent bore passage extending therethrough: upper bodymeans attached to and encircling said mandrels; a unitary tubular anchorslip encircling said dual mandrels and arranged on said mandrels inlimited slidable and pivotable relationship; said unitary slip having aplurality of teeth formed on diametrically opposite sides at oppositeends thereof, said teeth adapted to engage said grip the inner wall ofthe well casing; said anchor slip further having two sets of dualparallel bore passages therethrough each capable of receiving saidmandrels, said one set of dual passages intersecting said other set atan angle of about five degrees up to about thirtyfive degrees, wherebysaid anchor slip can be rotated from casing engaging position tononengaging position on said mandrels; packer means comprising aplurality of resilient annular packer elements and rigid containingmeans adjacent said resilient elements, said packer means encirclingsaid mandrels in a partially slidable relationship thereon and arrangedto abut said anchor slip; hydraulic actuation means located on saidmandrels and comprising piston means and cylinder means, said pistonmeans slidably engaging said cylinder means, and said piston means andsaid cylinder means each containing inner annular differential pressurearea surfaces arranged to communicate with post means through the wallof one of said mandrels; said differential pressure surfaces adapted toreceive fluid pressure through said port means and force said pistonmeans out of said cylinder means into abutment with said anchor slipthereby rotating said anchor slip and compressing said resilient packerelements into engagement with the well casing; locking means on saidmandrels for engaging said mandrel and maintaining said said anchor slipin said rotated position and said packer means in said compressedposition; shear means preselectively shearable to allow said anchor slipand said packer means to be released from said locking means at apredetermined desired time; releasing means in said packer arranged toabut said rotated engaged anchor slip and selectively rotate said anchorslip out of the engagement with said well casing; and, wherein saidlocking means further comprises a dual conical wedging collar slidablymounted on said mandrels and attached to said cylinder means, and aplurality of toothed wedge inserts located within said wedging collarbetween a conical inner wall in said collar and said mandrels, saidinserts arranged to be wedged against said mandrels by the conical innerwall of said wedging collar to force the toothed portion of said insertsinto engagement with the mandrels, said toothed portions having cammedteeth thereon arranged to allow said inserts to move in only onedirection on said mandrels.
 2. The well packer of claim 1 wherein saidlocking means further comprises a second dual conical wedging collarslidably mounted on said mandrels, said second collar being attached tosaid packer means and containing a plurality of wedge inserts in a dualconical cavity therein between said wedging collar and said mandrels,said inserts having cammed gripping teeth thereon in abutment with saidmandrels and arranged to allow movement in one onE direction on saidmandrels.
 3. The well packer of claim 2 wherein said releasing meanscomprises an elongated releasing member attached to said packer means,extending through said unitary slip, and having abutment means thereonarranged upon upward movement of said packer means to abut one side ofsaid slip and rotate said slip out of engagement with the casing wall;said slip being shearably and temporarily attached to said releasingmember in a non-engaging position in the casing by a shearable screwpassing through said slip and into said releasing member.
 4. The wellpacker of claim 3 wherein said shear means further comprises shearablepins within said packer means in abutting relationship with saidmandrels; and said packer means further comprises an upper cylindricalpacker head attached to the upper side of said rigid containing meansand encircling said mandrels; a retainer key sleeve means locatedconcentrically between said packer head and said mandrels, said keysleeve means having key retaining slots formed therein; retainer keyslocated in said slots and projecting radially inward through said slots;and, annular abutment ridges on said mandrels for receiving saidprojecting keys in longitudinal axial abutment, and internal, annularretention abutment shoulder means within said packer head arranged toabut said keys and maintain them engaged in said abutment ridges; saidpacker head further having an enlarged inner bore area adjacent saidinternal shoulder means adapted to receive said retainer keys uponupward movement of said packer head with respect to said retainer keysleeve means; said retainer key sleeve means arranged to abut said rigidcontaining means and said packer head and transfer downward axial forcesfrom said tubing string to said packer means and to transfer downwardforces acting on said mandrels to said packer means, and furtherarranged to allow shearing of said shearable pins and release of saidpacker means and anchor slip upon application of upward force on saidtubing string.
 5. A multistring well packer assembly capable ofisolating a plurality of annular areas in an oil well, said well packerassembly comprising: a plurality of tubular, cylindrical elongatedmandrels arranged in generally parallel, longitudinal alignment andadapted to be inserted longitudinally into an oil well; packer assemblymeans slidably and concentrically located telescopically about saidmandrels and containing a plurality of resilient compressible packerelements therein; releasing assembly means attached to said packerassembly means and releasably connected to said mandrels; one or moreelongated tubular receiving conduits securedly attached to saidreleasing assembly means and communicating coaxially with said mandrels;cupped cylindrical upper connector means attached to one or more of saidreceiving conduits and adapted to receive therein in yieldableconnection, additional tubular conduits from above; a first grippingassembly located slidably and concentrically on said mandrels below andattached to said packer assembly means and arranged to allowlongitudinal movement of said packer assembly in one direction on saidmandrels and to selectively retard said longitudinal movement in theopposite direction; unitary tubular anchor means mounted partiallyrotatably and slidably on said mandrels below said gripping assembly andarranged to abut said gripping assembly and rotate it into grippingengagement with the oil well casing; piston and cylinder means locatedbelow said anchor means in slidable concentric attachment on saidmandrels, said piston and cylinder means having a piston securedlyattached to said mandrels and a cylinder slidably mounted on saidmandrels and said piston; said cylinder arranged to move upward on saidmandrels toward said anchor means; one or more ports through the wall ofat least one of said mandrels communicating with a differential pressurearea between said piston and Cylinder, said differential pressure areaarranged to drive said cylinder from said piston in response tohydraulic pressure communicating through said ports; and, a secondgripping assembly attached to said cylinder and arranged to allow upwardmovement of said cylinder on said mandrels while retarding downwardmovement of said cylinder on said mandrels, and further arranged uponupward movement to abut said anchor means and further rotate said anchormeans into engagement with the oil well casing.
 6. The well packerassembly of claim 5 further comprising: anchor release means attached tosaid first gripping assembly and arranged to abut said anchor means uponupward movement of said gripping assembly, said release means abutmentoccurring at one side of said anchor means thereby providing selectiverotation of said anchor means out of engagement with the oil wellcasing; first shear means between said piston and said cylinder arrangedto secure said piston to said cylinder until sufficient hydraulicpressure through said ports forces said cylinder from said piston byshearing said first shear means; and, second shear means between saidanchor means and said release means arranged to prevent engagement ofsaid anchor means with the well casing until rotative force sufficientto shear said second shear means has been applied to said anchor means.7. The well packer assembly of claim 5 wherein said releasing assemblymeans further comprises an upper head, an intermediate tubular abutmentcollar, and a releasing key sleeve located concentrically within saidhead and said abutment collar and abuting said packer assembly means,said sleeve having a plurality of key slots through the wall thereof anda plurality of retaining keys located in said key slots and projectinginwardly through said wall of said sleeve and abutting said mandrels,said mandrels having parallel circumferential annular ridges thereonarranged to receive said keys therebetween in close fittingrelationship, said keys and ridges temporarily restraining longitudinalrelative movement between said sleeve and said mandrels; said uppertubular head having a lower projecting skirt arranged to abut the outersurfaces of said keys and maintain them engaged in said parallel ridges;said abutment collar having an inner annular space between said collarand said sleeve arranged to receive said keys from said slots and allowdisengagement of said sleeve from said mandrels upon upward movement ofsaid head lower skirt from abutment with said keys; and said upper headbeing shearably attached to said mandrels by shear means passing throughsaid head and abutting said mandrels above said parallel ridges anddirectly below a third annular ridge on said mandrels; said third ridgehaving a shear edge thereon arranged to shear said shear means passingthrough said head.
 8. The well packer assembly of claim 5 furthercomprising: collected sleeve means passing through and yieldablyabutting said releasing assembly means and said packer assembly meansand arranged to yieldably connect said releasing assembly means to saidpacker assembly means.
 9. The well packer assembly of claim 5 whereinsaid anchor means comprises a generally cylindrical gripping memberhaving a dual-axis bore passage therethrough for each mandrel of saidwell packer assembly, said each bore passage comprising two generallycylinderical intersecting bores passing longitudinally through saidgripping member, with the axes of said intersecting bores having anangle of intersection of from about five degrees up to about 35 degrees,said dual axis bore passages arranged to allow said member to pivotabout said mandrels from a non-engaging position to a gripping positionin the well casing; said gripping member having a plurality ofperipheral ridges formed at diametrically opposite sides and at oppositeends of said member, said ridges adapted to engage said well casing uponrotation of said anchor means.
 10. THe well packer assembly of claim 9wherein said first and second gripping assemblies generally comprise amultiple passage, inner conical surface wedging collar encircling saidmandrels and forming an annular conical space therebetween; and aplurality of conical shaped toothed wedge inserts located in saidconical space and in contact with said collar and said mandrels; saidteeth on said inserts arranged to cam over said mandrels in onedirection of movement therebetween, and to engage said mandrel uponattempted movement in the opposite direction.